1. Field of the Invention
This invention relates generally to a closed-loop system for the collection and transfer of solar energy wherein heat transfer fluid circulates between a solar energy collector exposed to the sun's rays and a heat exchanger incorporated with a domestic hot water storage tank and in particular is directed to structural features of the solar energy collector.
2. Description of the Prior Art
Rising energy costs have created a demand for solar energy water heaters for home use by justifying the initial investment in terms of the actual savings afforded by the use of such equipment. A proven popular system for heating water for home use by the sun's rays and capable of careful control necessitated by the changing availability of solar radiation at a given location is the closed-loop in which a heat transfer fluid is circulated between a solar energy collector and a heat exchanger associated with a hot water storage tank. The solar energy collectors, which are the heart of the closed-loop systems, are basically similar in comprising a conduit for the fluid enclosed in a glass covered housing. The conduit is usually a series of parallel, coplanar, pipe sections connected either in series to provide a single serpentine path or in parallel providing a plurality of paths and is made of heat conductive material, metal or plastic, having a black surface for maximum heat absorption.
Various proposed constructions to provide a non-circular cross-section for the single serpentine path conduit, which single path is favored for the closed-loop system, and to bring the parallel sections close together for improved efficiency have heretofore been impractical or have proven to be excessively costly to manufacture as a reliable product. To protect the consumer from such unreliability, various codes for efficiency and durability have been established by federal, state and local government agencies, often requiring actual testing of the solar energy collector before marketing is authorized.
There is, therefore, a pressing need for a highly efficient, relatively light weight collector of manageable size for shipping and installation, which is reliable and durable for a long life of trouble-free service in a wide variety of climates and which will comply with the established codes.